The present invention relates to improvements in electrophotographic reproducing machines and methods, and it relates particularly to an improved apparatus and method for forming an electrophotographic image, in which contact reflection printing and a contact transmission printing methods are employed.
The conventional methods for forming an electrophotographic images are the electrofax method and the xerographic method. These methods have been suitably employed only with original documents of high image density and contrast. In such methods, it is impossible to obtain an image which is clearer or better than the original image consequent to the limitations of the developer density and paper tint and accordingly, if the original image to be produced is low in the density and contrast, a poor image is reproduced. In the methods of producing an electrographic image as above described, the optical image projecting system is generally employed, the contact reflection printing system not being practiced, althugh the latter system has many advantages in comparison with the former. Thus, in the reflection printing system no optical projecting system employing lenses and a focussing space are needed, hence the miniaturization of the apparatus is possible, the phenomenon of the synchronous phase-out and the obscure printed image are minimized, and a high speed copying is possible. However, in the contact reflection printing system, the original image is exposed, hence the image reproduced is of extremely low density and contrast, even if an original document bearing an image of a high density and high contrast is used.
Thus, in the conventional method for forming an electrophotographic image, the optical image projecting system is not suitable for copying an original document of low density and low contrast, and the contact reflection printing system is not applicable, even where the original image is of high density and contrast.